JP2005077552A - Lens complex optical element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a lens complex optical element which can dissolve the problem of size increase and weight increase of an optical apparatus when a planar part of an optical glass plate having a prescribed optical function is made to be a lens surface, which is excellent in environment resistance and which can be manufactured inexpensively. <P>SOLUTION: In order to form the lens complex optical element by laminating a lens part 9 on a flat surface of a polarizing prism 8, a molding die 10 is used, a resin block 11 consisting of a transparent resin is supplied to a transferring surface 10a of the molding die 10 and then is heated. A lens forming surface 12a of the glass plate 12 constituting a polarizing prism 8 is pressed to molten or softened resin to transfer the transferring surface 10a and the resin is irradiated with UV by a UV irradiation device 13 to form the lens part 9. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention provides a glass plate having a predetermined optical function, such as a prism, a half mirror, and a reflecting mirror, and a curved lens portion on a surface portion where at least one of the light incident surface side and the light emitting surface side is planar. The present invention relates to a laminated lens compound optical element and a manufacturing method thereof.

  For example, an optical pickup device is used to read information from or write information to an information recording medium including an optical disk. Here, CD (Compact Disc) and DVD (Digital Video Disc) coexist as information recording media, and information reading from a CD, information writing to a DVD, and information reading are performed in a single manner. An apparatus that can be used by the above apparatus has been put into practical use. These CDs and DVDs have different disc thicknesses, and the wavelength of the irradiated light is 780 nm in the CD system, 650 nm in the DVD system, and the numerical aperture (NA) is also different. Therefore, it is necessary for the optical pickup to switch the laser light source when reading information from a CD and when writing or reading information on a DVD. In order to switch the light source, for example, a polarizing prism is used. In this polarizing prism, light having a wavelength of 780 nm, which is a laser light source for CD, is transmitted, and light having a wavelength of 650 nm, which is a laser light source for DVD, is reflected. The space from the prism to the information recording medium can be shared, so that the optical pickup can be made smaller and more compact.

  In this case, in order to correct aberrations such as astigmatism, spherical aberration, and coma that occur when laser light passes through the polarizing prism, either alone or in combination, an optical element such as a spherical or aspherical lens is used. It is necessary to intervene. In various optical devices including optical pickups, convex spherical lenses, concave spherical lenses, and cylindrical surfaces are also used in the optical path to focus the light beam and shape the beam pattern to a desired shape. Or a toroidal surface or other aspherical lens may be provided.

When using an optical element having an optical function such as a polarizing prism in combination with various lenses as described above, it is necessary to give the lens incorporated in the device self-supporting property, which increases the thickness of the lens, The optical device as a whole is increased in size and weight. In order to give a lens surface to a transparent substrate, it is also possible to make the transparent resin into an integrally molded product by injection molding means, etc., so that the integral molding can reduce the size and size of the optical device. Can do. However, there is a problem that it is inferior in environmental resistance such as temperature and humidity. Also, a method of giving a lens function to a prism or the like by injection molding glass can be considered, but it becomes very expensive.
Japanese Patent Laid-Open No. 10-27378

  Accordingly, in the present invention, the problems of increasing the size and weight of the optical device, which are various problems that occur when the flat surface of the optical glass plate having a predetermined optical function is used as the lens surface, are eliminated, and the environment resistance is improved. It is desirable to be able to form a lens composite optical element that is excellent in manufacturing and inexpensive.

  In order to solve the above-described problems, the present invention is to laminate a lens portion having a curved outer surface on a flat surface of a glass plate functioning as a predetermined optical element by a molding means. Thus, the lens composite optical element is formed.

  Here, the glass plate used in the present invention has a certain optical function, and at least one of the light incident surface and the reflective surface has a flat portion. Examples of the glass plate include a prism, a reflecting mirror, and a half mirror. The prism is formed as a polarizing prism having one side as a polarizing surface.

  The lens portion formed on the surface of the flat surface of the glass plate includes a convex lens, a concave lens, an aspheric lens that is a symmetric surface in the rotation direction, and a curved surface that is asymmetric in the rotation direction such as a cylindrical surface or a toroidal surface. . Therefore, the lens portion has a curved surface shape according to the purpose, such as aberration correction and beam pattern shaping.

  Therefore, the lens portion is formed of a transparent synthetic resin and is laminated on the glass plate surface using a mold having a transfer surface. In order to transfer the shape of the transfer surface, the synthetic resin is heated to be softened or softened. Melt. Then, after the transfer is completed, the synthetic resin is cured, but an ultraviolet curable resin or a thermosetting resin can be used for rapid curing. The lens portion is desirably formed in a substantially thin film shape having a small curvature, for example, a maximum thickness of 1 mm or less, on condition that a desired function is exhibited.

  In this way, by using a mold having a transfer surface to a glass plate, the lens part is formed as a synthetic resin film on the surface of the flat part of the glass plate, so that a small and compact lens composite optical element can be manufactured at low cost. it can. In addition, it is only necessary to obtain a desired curved surface, and since self-supporting property as a lens is not required, the film can be substantially formed into a film and the weight can be reduced. And, by forming the lens part as a thin film and firmly fixing it to the surface of the glass plate in this way, the overall linear expansion coefficient is substantially replaced by the coefficient of the glass plate, and the temperature and humidity It is excellent in environmental resistance, such as being able to suppress fluctuations in the curvature of the lens curved surface due to changes.

  Therefore, as a configuration of the lens composite optical element of the present invention, a transparent synthetic resin film is laminated by a molding means on a surface of a flat surface of a glass plate functioning as a predetermined optical element, with a lens portion having a curved outer surface Thus, an element having an optically combined function can be compactly incorporated in an optical apparatus.

  Further, as a method for manufacturing a lens composite optical element in which a lens part is formed on a flat part surface of a glass plate functioning as a predetermined optical element by molding means, an ultraviolet curing is applied to a molding die having a curved transfer surface of the lens part. By placing a resin lump made of resin or thermosetting resin, the resin lump is softened or melted by heating, the glass plate is brought into contact with the mold, and pressed as necessary. It is characterized in that a synthetic resin film is formed on the glass plate by transferring the transfer surface of the mold to the resin, the synthetic resin film is cured, and the mold is released.

  Next, Example 1 of the present invention is shown. In the first embodiment, the lens composite optical element is incorporated into the optical pickup device. FIG. 1 shows a schematic configuration of a main part of the optical pickup device. In the figure, 1 is a first laser light source and 2 is a second laser light source. Laser light having a wavelength of 780 nm is emitted from the first laser light source 1 and information is read from the CD 3. Further, a laser beam having a wavelength of 650 nm is emitted from the second laser light source 2, and information is written to and read from the DVD 4. Then, the laser beams from the first and second laser light sources 1 and 2 are transmitted through the collimator lenses 5 and 6 to form parallel light beams, and the laser beam is recorded on the information recording composed of CD3 or DVD4 by the objective lens 7. It is designed to converge toward the medium.

  In the figure, reference numeral 8 denotes a polarizing prism. By this polarizing prism 8, the laser light from the first laser light source 1 and the laser light from the second laser light source 2 take the same optical path. The polarization prism 8 is formed with a polarization separation film 8a. The polarization separation film 8a has a function of transmitting all the P-polarized light components and reflecting all the S-polarized light components in the incident light. Therefore, by making the laser light from the first laser light source 1 P-polarized light, the laser light from the first laser light source 1 is transmitted through the polarizing prism 8, and the second laser light source. The laser light from 2 is converted to S-polarized light and reflected to the polarization separation film 8 a of the polarizing prism 8. As a result, the same optical path is taken until the laser beams from the first and second laser light sources 1 and 2 are irradiated from the polarizing prism 8 to the information recording medium.

  The laser light from the first laser light source 1 passes through the polarizing prism 8, but this polarizing prism 8 has non-uniform thickness, and astigmatism occurs. In addition to astigmatism, other aberrations such as spherical aberration may occur depending on the configuration of the optical device. In order to correct these aberrations, an aberration correction lens unit 9 is provided on the incident surface of the laser beam from the first laser light source 1 in the polarizing prism 8. The lens portion 9 is formed of a thin film-like concave lens made of a transparent resin, and is laminated on the planar surface of the polarizing prism 8. The polarizing prism 8 and the lens unit 9 are configured as a lens composite optical element as a single optical element.

  A method of forming a lens composite optical element in which the lens unit 9 is laminated on the polarizing prism 8 will be described with reference to FIG. For this purpose, a mold 10 having a transfer surface 10a for transferring the curved surface shape of the lens portion 9 is used. As shown in FIG. 2A, the molding die 10 has a transfer surface 10a facing upward, and a transparent synthetic resin lump as a material of the lens portion 9 molded on the transfer surface 10a. That is, the resin mass 11 is supplied. Then, the resin mass 11 is heated until it becomes softened or melted. For example, the resin lump 11 can be heated by attaching a heater to the mold 10 and heating the entire mold 10.

  When the resin block 11 placed on the transfer surface 10a of the mold 10 is softened or melted, a polarization separation film 8a is formed on the glass plate 12 configured as the polarizing prism 8, as shown in FIG. The lens portion 9 is formed by bringing the lens laminated surface 12a opposite to the surface to be in contact with the softened or melted resin on the transfer surface 10a of the mold 10. Here, the lens unit 9 may be formed after the polarization separation film 8a is formed in advance, but it is preferable to perform the stage before the formation of the polarization separation film 8a on the glass plate 12 in terms of subsequent processes. Further, the upper end portion of the mold 10 and the glass plate 12 are not brought into contact with each other in order to prevent air bubbles from entering when the lens portion 8 is formed. Even if the resin is melted, it has a fairly high viscosity, and rises to a certain extent from the transfer surface 10a due to surface tension. Even if the glass plate 12 is not brought into contact with the molding die 10, a certain amount of resin is obtained. A pressing force can be applied, and sufficient transfer accuracy can be obtained. Then, by this applied pressure, the bubbles are pushed out to the outer peripheral side along the surface of the lens laminated surface 12a and the surface of the transfer surface 10a, and at the lens portion 9, bubbles do not remain at least in the effective area. .

  Here, even if the resin is melted, a fairly high viscosity state is maintained, so that the amount of the resin mass 11 supplied to the mold 10 is accurately controlled as indicated by the phantom line in FIG. As a result, the resin swelled on the transfer surface 10 a comes to adhere to the glass plate 12 side and does not flow down along the peripheral body portion of the mold 10. Then, by forming a chamfered portion 10b having a taper shape of approximately 45 ° outwardly on the outer peripheral portion of the transfer surface 10a, even if excess resin on the transfer surface 10a side protrudes to the outside, It will adhere to this chamfer 10b. As a result, the surplus resin does not flow down to the peripheral body portion of the mold 10 and the mold releasability of the mold 10 from the glass plate 12 does not deteriorate. The resin that has entered the chamfered portion 10b remains on the glass plate 12 side at the time of mold release, but since this portion is located outside the effective area, there is no influence on the optical function. Don't give.

  When the resin is laminated on the lens lamination surface 12a of the glass plate 12 as described above, the resin is cured. For this purpose, as shown in FIG. 2C, the resin is irradiated with ultraviolet rays from the ultraviolet irradiation device 13 from the upper side of the glass plate 12. Here, since the glass plate 12 is a stage before the polarization separation film 8a as the polarizing prism 8 is formed, the ultraviolet rays from the ultraviolet irradiation device 13 are transmitted through the glass plate 12 and reliably and efficiently resin. Is irradiated. When the resin is cured by the irradiation of ultraviolet rays, the lens portion 9 is laminated on the lens lamination surface 12a by separating the mold 10 from the glass plate 12, as shown in FIG. Therefore, a release film is formed in advance on the transfer surface 10a of the mold 10 in order to improve the resin releasability by the mold 10.

  After the lens portion 9 is formed on the lens lamination surface 12a of the glass plate 12, the polarization separation film 8a is laminated on the opposite surface by means such as vacuum deposition or film adhesion. Thereby, a lens composite optical element composed of a laminate of the polarizing prism 8 and the aberration correcting lens unit 9 is formed.

  Here, since the lens portion 9 formed in the polarizing prism 8 is for correcting aberrations such as astigmatism, it is a concave spherical lens or a rotationally symmetric aspherical surface in the concave lens. Although it is composed of a lens, it can be formed with a very small curvature, that is, close to a planar shape. In addition, since the lens does not need to be self-supporting, for example, even the thickest part can be formed into a thin film having a thickness of about 0.7 mm and a minimum thickness of 0.1 mm or less. it can. Therefore, a small, compact and lightweight lens composite optical element can be formed at low cost and with high accuracy. In addition, the lens portion 9 that is firmly fixed to the polarizing prism 8 with a thin film in this way has its linear expansion coefficient substantially replaced with the linear expansion coefficient of the glass constituting the polarizing prism 8. As a result, the temperature dependence of the refractive index is almost eliminated, and the environment resistance is excellent.

  In the second embodiment, as shown in FIG. 4, in the optical configuration in which the laser light emitted from the laser light source 20 is reflected by the half mirror surface 21 a of the beam splitter 21, the incident surface 21 b of the beam splitter 21. The lens portion 22 having a convex spherical shape for controlling the degree of divergence of the laser beam incident on the lens is formed integrally with the beam splitter 21. The lens unit 22 is directly laminated on the incident surface 21 b of the beam splitter 21. As a result, the light beam expanding as shown by the dotted line in FIG. 4 is controlled to be a small-diameter beam pattern as shown by the solid line in FIG. The

  As described above, the lens portion 22 is integrally formed with the beam splitter 21 so that the outer peripheral portion of the convex lens does not have a thickness, that is, the outer diameter is slightly larger than the spot diameter on the light incident surface 21b. By forming the lens portion 22, a lens composite optical element in which a thin film lens is provided integrally with the beam splitter 21 is formed. Here, the beam splitter 21 joins two triangular prism glass plates, and a half mirror surface is formed on the joining surface. The half mirror surface 21a is formed on one of the two glass plates, and the other side is formed. The lens portion 22 is formed on the glass plate and bonded and fixed to each other by means such as adhesion. Accordingly, in the glass plate 23 on which the half mirror surface is not formed, the lens portion 22 is laminated on the flat surface 23a that becomes the incident surface 21b when the beam splitter 21 is formed, according to the procedure shown in FIG.

  That is, as shown in FIG. 5A, the resin mass 25 constituting the lens portion 22 is placed on the mold 24 having the convex lens transfer surface 24a, and the resin mass 25 is heated to transfer the resin mass 25. The resin is softened or melted on the surface 24a. In this state, as shown in FIG. 5B, the glass plate 23 is brought into contact with the resin in the transfer surface 24a. At this time, in order to eliminate air bubbles, the flat surface 23a of the glass plate 23 is brought into a non-contact state with the molding die 24 so as to transfer the die. Further, when the convex shape that becomes the lens portion 22 is accurately transferred to the resin laminated on the surface of the glass plate 23, the ultraviolet irradiation device 26 irradiates the resin with ultraviolet rays as shown in FIG. To cure the resin. When the resin is completely cured, the lens portion 22 is laminated on the glass plate 23 by separating the mold 24 from the resin as shown in FIG. Thereafter, the triangular prism-shaped glass plate 23 is bonded to another triangular glass plate on which a half mirror surface is formed, so that the beam splitter 21 integrally provided with the lens portion 22 is obtained.

  The lens surface formed on the glass plate may have a curved surface shape that is not necessarily a spherical shape or an approximate spherical shape, for example, the transfer surface of the mold is a cylindrical surface. As a result, a cylindrical lens or the like is formed on the glass plate, and the incident beam having a circular cross section can be shaped into an elliptical pattern. In addition, the resin forming the lens portion is not cured by ultraviolet rays, and when a resin that cures by heat is used, the mold may be heated to a temperature higher than the curing temperature of the resin. Furthermore, the lens can be formed by filming not only on one surface of the glass plate but also on a plurality of surfaces (for example, the light emission side surface of FIG. 4), and also on different portions on the same surface. can do.

It is a schematic block diagram which shows the state comprised as a polarizing prism with a lens as a lens compound optical element in Example 1 of this invention, and incorporating in the optical pick-up apparatus. It is explanatory drawing which shows the method of forming a lens part in the glass plate which comprises the polarizing prism of FIG. It is a principal part enlarged view which shows the other form of the shaping | molding die used in order to implement the method of FIG. It is a structure explanatory view of a beam splitter with a lens as a lens compound optical element in Example 2 of the present invention. It is explanatory drawing which shows the method of forming a lens part in the glass plate which comprises the beam splitter of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 8 Polarizing prism 8a Polarization separating film 9, 22 Lens part 10, 24 Mold 10a, 24a Transfer surface 11, 25 Resin lump 12, 23 Glass plate 13, 26 Ultraviolet irradiation device

Claims (5)

A lens composite optical element characterized in that a transparent synthetic resin film is laminated on a surface of a flat surface of a glass plate functioning as a predetermined optical element by a molding means on a lens part having a curved outer surface. The lens composite optical element according to claim 1, wherein the glass plate is any one of a prism, a half mirror, and a reflection mirror. The lens composite optical element according to claim 1, wherein the lens unit is for performing aberration correction or beam shaping. 2. The transparent synthetic resin is an ultraviolet curable resin, and the ultraviolet curable resin is configured to mold a lens portion made of the ultraviolet curable resin with a molding die having a curved transfer surface. The lens composite optical element described. A method of forming a lens portion on a flat surface of a glass plate functioning as a predetermined optical element by a molding means,
A resin lump made of an ultraviolet curable resin or a thermosetting resin is placed on a molding die having a curved transfer surface of the lens part, and the resin lump is softened or melted by heating,
By bringing the glass plate into contact with the resin on the transfer surface of the mold and transferring the shape of the transfer surface of the mold to the resin, a synthetic resin film is formed on the glass plate,
A method for producing a lens composite optical element, comprising curing the synthetic resin film and releasing a mold.

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